Acoustic streaming for direct delivery of therapeutics into tissue.

Ultrasound has been used in medical drug delivery but largely for altering membrane permeability. We are investigating acoustic streaming for delivery of therapeutics, such as drug molecules or other particulates, into brain tissue, with other applications for the future. Acoustic streaming potentially can enhance fluid and particle flux in interstitial pathways in tissue. The conventional equations that describe streaming in fluids are not directly applicable to porous media such as the brain. In this study, a modified Biot equation is employed to develop a theoretical framework to account for the attenuation mechanisms dominant in acoustic streaming in porous media. The analytical solutions obtained for isotropic, homogeneous media are presented and compared with experiments conducted on gel phantoms, and with results reported for streaming in live monkey brains. The dependence of streaming‐induced therapeutic transport on acoustic parameters and tissue properties are investigated. The theoretical frame...